day6.md

Day 6

• Closures, Part One

Creating basic closures

• Type functionName = { ... }

let driving = {
  print("I'm driving in my car")
}

driving()

Accepting parameters in a closure

• Type functionName = { (parameter: Type) in ... }

let driving1 = { (place: String) in
  print("I'm going to \(place) in my car")
}

driving1 ("London")

Returning values from a closure

• parameter와 in 사이에 -> Type을 넣어줌.
• return returnValue

let driving2 = { (place: String) in
  print("I'm going to \(place) in my car")
}

let drivingWithReturn = { (place: String) -> String in
  return "I'm going to \(place) in my car"
}

let message = drivingWithReturn("London")
print(message)

Closures as parameters

• closure를 일급 객체( 여기서는 parameter)로 사용할 수 있음

let driving3 = {
  print("I'm getting ready to go.")
}

func travel(action: () -> Void) {
  print("I'm getting ready to go.")
  action()
  print("I arrived!")
}

travel(action: driving3)

Trailing closures syntax

func travel1(action: () -> Void) {
  print("I'm getting ready to go.")
  action()
  print("I arrived!")
}

travel1() {
  print("I'm driving in my car")
}

travel {
  print("I'm driving in my car")
}